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What You Need to Know Before Buying Neem Oil for Your Plants

Neem oil has risen in popularity especially during the pandemic, mainly because of its effect on plants' leaves- it makes them 'shiny'. Unfortunately, many plant enthusiasts buy this product without really understanding what it's really used for. For this reason,  cheaper "neem oil" variants have become available in the market today but they do not deliver the best results expected from the product.

So I decided to write this article with the intention of educating my fellow Filipino gardeners about neem oil, and how to choose a good quality neem oil that gives you the most bang for your buck. 

Neem Oil and its Benefits in Gardening

As an advocate of sustainable gardening, I prefer non-chemical solutions in managing pests. In many instances, using synthetic chemicals to control pests often create harmful effects on our environment and even expose our own family to health risks. However, finding a good balance between efficacy and its environmental impact can be a difficult choice.

Fortunately, neem oil is the only bio-pesticide that is not only proven effective in controlling more than 200 kinds of garden pests, but is also environment-friendly. Neem oil kills insects at all stages of its development - from egg, larvae to adulthood, including the most common pest problems like aphids, spider mites, scale, leaf hoppers, white flies, mealybugs, caterpillars, thrips, slugs, flea beatles and the like. 

It is important to note that neem oil does not  kill insects on contact.  What it does is to work internally within the bug's biological system by causing it to stop feeding and lose fertility, until it dies eventually. The insect needs to be exposed to neem oil by ingesting a portion of the plant that has been sprayed with a neem solution. This is why it is not harmful to bees, earthworms and other beneficial insects that do not feed on plants. 

Neem oil is also effective on the insect's larvae by eradicating them before they start wreaking havoc on your plants. Likewise, it is proven effective on harmful soil-bound nematodes that often destroy the plant's root system.  In addition, it has some anti-fungal properties that prevent common fungal diseases like mildews, black spot, scab, rust, leaf spot, anthrachnose and tip blight.

Neem oil is bio-degradable and it does not accumulate in the soil or plants regardless of the number of times you use it.  It is generally safe to use around humans and pets. Studies have shown that ingesting plant leaves that have been sprayed with neem oil does not cause any permanent harm on mammals.  Neem has been used as bio-pesticide in India for more than 100 years, and has been reported as generally safe on humans and animals.


Why choose Pure Cold-Pressed Neem Oil

What makes neem oil most effective as a bio-pesticide is this compound called "Azadirachtin" that is found mostly in the neem seeds. When buying Neem Oil,  look for the "Pure Cold-pressed Neem Oil" variant.  In a cold-pressed extraction process, neem oil is obtained by pressing or crushing the seeds or subjecting it to a certain regulated low temperature in order to extract the oil.  Pure cold-pressed neem oil is the highest quality because it preserves most of the beneficial compounds found in neem seeds, particularly the "azadirachtin".    

Many of the cheaper neem oil bottles sold in the market use a neem oil variant that uses an extraction process to separate residual neem oil, after extracting "azadirachtin".  The resulting product is called "Clarified Hydrophobic Extract of Neem Oil"  or simply "Neem Oil Extract", which is the residual product after removing its azadirachtin content. In other words. these products are still extracts from neem oil but they do not contain this powerful azadirachtin substance.  Although these cheaper versions could still retain some pesticide and fungicidal properties to a limited extent,  many of these products have been diluted with a carrier oil to increase their volume and sell cheaper in the market. This makes their effect on plants  oftentimes questionable.

So how do you know if you are buying the right stuff?   Pure cold-pressed neem oil emits a strong nutty/ garlic aroma.  Many would find its smell unpleasant, but this is what works wonders for your plants, and it also serves as a repellant against many insects. Other neem oil variants have a milder aroma because they have already been diluted (usually mixed with vegetable oil). You know if you are buying pure, unadulterated neem oil when the smell is strong (but tolerable).  

How to Use Neem Oil

If you are using pure cold-pressed neem oil, you only need a small amount for every use.  It's actually more economical. Simply mix 1 teaspoon (5ml) per liter of water. Since oil doesn't mix well with water, you need a surfactant in order to blend it well. For this, use 1 teaspoon of any mild organic liquid soap, or if this is not available, use a few drops of dishwashing liquid.  I would usually recommend castile soap because it has natural insecticidal and anti-bacterial properties that complements the powerful effects of neem oil. If the pest infestation is heavy, you can increase the neem dosage to up to 2 teaspoons for every liter of water.  

Mix all of these ingredients in a spray bottle and then shake it well until oil and water no longer separate. Use this solution to spray generously on plant leaves, stem and roots at dawn or late in the afternoon. If the infestation is heavy, repeat application after 2-3 days. Once the pests are controlled, a regular weekly application is recommended as a preventive measure. 


Why you shouldn't buy "Ready-to-Use Neem Oil Spray"

Also in recent months, there has been a proliferation of sellers marketing their "Ready-to-Use Neem Oil Spray"  online. They package their products in very nice bottles and infuse different fragrant aromatic scents. Some would even call  them as "Pure Neem Oil".  A naive customer is easily fooled because they think they are getting good value for their money. 

It is important to note that neem oil is bio-degradable once it is mixed with water. After mixing it in water, it starts to break down within 45 minutes and and its efficacy diminishes over the next 48 hours.  This is why I advise against storing or using any mixed solution that has been left in the spray bottle for more than 2 days.

The active neem oil components (if any) in these "Ready-to-Use Neem Oil Spray" products have already disintegrated and are no longer effective by the time this product reaches you. To put it bluntly, you are completely wasting your money if you buy these ready-to-use neem spray products. Without the active ingredients in neem oil, what remains in the solution is the neem fatty acid which has minimal beneficial effect on plants, except perhaps to make them a little shiny. This is no different from using any vegetable oil.  

Whereas if you buy a high quality cold-pressed neem oil, you can use this for several rounds, and simply store the unused portion until needed. The shelf life of a good quality pure neem oil is around 18 to 24 months. 


Some Important Reminders

While neem oil is generally safe around humans and pets, it is advised that you keep it away from small children, as in any substance that you would use in the garden. While neem oil has been known to have beneficial effects on the skin and hair, always consult a physician before applying it on your skin. It is better to take necessary precautions like using gloves or a face mask when using neem, especially if you suspect that you are pregnant. Ingesting neem may cause trembling and other side effects in pets (cats and dogs), which are usually not fatal. Always use any gardening product with caution and consult your veterinarian before using neem oil on pets.



"Using Neem Oil " by Shannon McKee,

"Neem Oil Facts (Definitive Safety Guide)" 

"Azadirachtin vs. Clarified Hydrophobic Extract of Neem Oil"

"The Benefits of Neem Oil,"

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